1. Field of the Invention
The present invention relates to a method and apparatus for recognizing a preceding vehicle traveling on a traffic lane on which a subject vehicle is traveling.
2. Description of the Related Art
Apparatuses for recognizing a preceding vehicle have been used to carry out a vehicle speed control, so that the distance between the preceding vehicle and a subject vehicle is brought close to a definite value.
In a prior art apparatus for recognizing a preceding vehicle ahead of a subject vehicle, it is determined whether or not the preceding vehicle is within a preceding vehicle recognizing region ahead of the subject vehicle. As a result, determination of the preceding vehicle is carried out immediately in accordance with whether or not a preceding vehicle is within the preceding vehicle recognizing region. This will be explained later in detail.
In the above-described prior art preceding vehicle recognizing apparatus, however, when the traffic lane on which the preceding vehicle is traveling is curved, the preceding vehicle may be lost within the preceding vehicle recognizing region, even though the preceding vehicle keeps traveling on the same traffic lane. This erroneous recognition of the preceding vehicle would fluctuate the vehicle speed control.
It is an object of the present invention to provide a method and apparatus for surely recognizing a preceding vehicle even when traveling along a curved traffic lane.
According to the present invention, in a method for recognizing a preceding vehicle traveling on a traffic lane on which a subject vehicle is traveling, it is determined whether or not the preceding vehicle is deviated from a preceding vehicle recognizing region ahead of the subject vehicle. Then, when the preceding vehicle is deviated from the preceding vehicle recognizing region, it is determined whether or not the traffic lane is curved while maintaining recognition of the preceding vehicle. When the traffic lane is curved, it is determined whether or not the preceding vehicle has entered the preceding vehicle recognizing region for a predetermined time period while maintaining the recognition of the preceding vehicle. As a result, the recognition of the preceding vehicle is maintained or released in accordance with whether or not the preceding vehicle has entered the preceding vehicle recognizing region for the predetermined time period.
Also, in an apparatus for recognizing a preceding vehicle traveling on a traffic lane on which a subject vehicle is traveling, a preceding vehicle recognizing section sets a preceding vehicle recognizing region ahead of the subject vehicle. A preceding vehicle determining section determines whether or not the preceding vehicle is within the preceding vehicle recognizing region. A curved road determining section determines whether or not the traffic lane is curved while maintaining recognition of the preceding vehicle, when the preceding vehicle is deviated from the preceding vehicle recognizing region. The preceding vehicle recognizing section further determines whether or not the preceding vehicle has entered the preceding vehicle recognizing region for a predetermined time period while maintaining the recognition of the preceding vehicle, when the traffic lane is curved. As a result, the recognition of the preceding vehicle is maintained, when the preceding vehicle has entered the preceding vehicle recognizing region for the predetermined time period. On the other hand, the recognition of the preceding vehicle is released, when the preceding vehicle has never entered the preceding vehicle recognizing region for the predetermined time period.